Connector bolt and method of making the same



y 14, 1942- P. J. MCCULLOUGH ETAL 2,289,516

CONNECTOR BOLT AND METHOD OF MAKIIiG THE SAME LLOUGH ENTORS FIG.8.

' INV PAUL J. McCu JOSEPH PAVELKA 1 Original Filed Oct. 17, 1956 EEEQ , FIGAOI.

v 7 ATTORNEY.)

Patented J uly 14, 1942 CONNECTOR BOLT AND DIETHOD OF MAKING THE SAME Paul J. McCullough and Joseph Pavelka, St. Louis, Mo.; said McCullough assignor to said Pavelka Original application October 17, 1936, Serial No. 106,119, now Patent No. 2,238,911, dated April 22, 1941. Divided and this application November 12, 1940, Serial No. 365,256

15 Claims.

The invention relates to electric connectors of the split bolt type.

Reference is made to applicants copending application Serial No. 106,119, filed October 17,.

1936, of which the present application is a di- 6 cooperates with the base of the die to give the i i cross bar of the U member a flattened head with One of the objects of the invention is to avoid a finished hexagonal contour as indicated in Figundue distortion of the metal used in the formaure 8. tion of the bolt, whereby a stronger finished In the next operation the U member 4 is placed product is obtained and pressure on the exover an anvil or mandrel 1 (Figures 9, 10, 11), pensive dies used in forming the bolt is reduced having a cross section contour with convex sides, and the dies are given a longer life, thereby reand the legs of the blank are each bent over ducing the cost of the connectors. these sides of the anvil by movements of the con- Another object of the invention is to stamp out cave threaded faces of cooperating dies 8. This a connector bolt of this type with even threads one operation gives the legs of the blank a conthroughout the length of the bolt legs without recavo-convex form and impresses the threads in quiring the trimming of surplus metal. the convex faces of the legs, the legs remaining These and other detail objects of the invention substantially the same thickness from edge to will be apparent from the following description edge and remaining substantially the same and from inspection of the accompanying draw- 2.) length. The lugs X on the anvil I engage the ing in whichedges of the blank as it is bent around the anvil Figure 1 is a perspective view of the finished and prevent the edges from thinning out. The bolt only. shaping of the bolt legs to ar'cuate contours and Figure 2 is a side elevation of the bolt applied the impressing of the threads is efiected without to a pair of conducting wires with a washer and causing any substantial flow of the metal and, nut assembled with the bolt to clamp the wires in accordingly, harder material may be used than place. A washer retaining wire is indicated as would be practical with stamped out bolts as disclosed in the above-mentioned application. previously formed in which the legs are com- Figure 3 is a perspective view of a flat blank pressed between die parts by heavy pressure and from which the bolt is formed. are substantially reduced in sectional area dur- Figures 4, 5, 6 and 7 are transverse sections ing this process and portions are extruded bethrough a forming die and punch illustrating the yond the compressing elements of the dies and first steps in the formation of the bolt. must betrimmed away before the threads are Figure 8 is a transverse horizontal section on impressed to form the finished product. the line 8---8 of Figure 7'. The concavo-convex cross section of the legs Figure 9 is a section through a shaping and produced by the last operation described is well threading die and anvil with the blank shown in illustrated at 9 in Figure 1. Figure 7 in place to be operated upon. The fig- In addition to the advantages attending the ure is taken on the line 9-9 of Figure 10. manufacture of the bolt as described above, the

Figure 10 is a transverse horizontal section concavity along the inner face of the leg accomtaken on the line l0i0 of Figure 9. modates a wire I! which retains the washer Figure 11 corresponds to Figure 10 but shows resting upon the electrical conduit wires-E and the parts at the completion of the operation illuspreferably having an upstanding portion which trated. extends through a nut l6 and is flanged at ll Figures 12 and 13 illustrate, respectively, modiover nut Hi to hold the nut assembled with the fled anvil structures which may be used in the bolt. This retainer structure is further illusoperations indicated in Figures 9, l0 and 11. trated and described in the above-mentioned co- The blank I illustrated in Figure 4 may be pending application. stamped from flat rolled sheet or bar material It is not essential that 'the concavity in the and is of substantially uniform thickness from 5 bolt leg be arcuate and Figures 12 and 13 illusend to end with the opposite faces comprising trate, respectively, anvils I8 and 19 which may parallel plane surfaces and possesses elongated be substituted for anvils l and will give the substantially parallel grain structure as is charinner face of the bolt leg a concave contour acteristic of rolled metal stock. The blank is formed of three or two straight faces accordfirst placed into a forming die 2 and a punch 3 ingly.

descends, as indicated in Figures 4, 5 and'6, bending blank i into the U-shaped structure indicated at l in Figure 6. The U member 4 is then transferred to die 5, Figure 'I, in which the punch Those familiar with the art will readily apprehend from the description and the accompanying drawing that the objects of the invention stated in the introductory portion of this specification may be attained to a' marked degree. The forming of the bolt requires comparatively little pressure by the dies because the flat shaped portions of the blank are bent around the anvil by the threading die rather than being changed in cross sectional area by heavy pressure which results in extrusion, changing its grain formation and putting heavy load upon the dies. The threads will be sharp and full from edge to edge of the leg. Aside from drilling the holes for the ends of retainer'wire II, no machine work on the bolt is required and it may be used as it comes from the bending and forming operation.

It is obvious variations in the steps and details of the bolt and its method, other than those referred to, may be made without departing from the spirit of the invention and the exclusive use of such modifications as come within the scope of the claims is contemplated.

What is claimed is:

1. The method ofmaking a connector bolt which is characterized by bending a bolt leg forming element of rectangular cross section, of suflicient width and thickness to be substantially rigid, into a concavo-convex cross section of substantially the same cross sectional area and simultaneously stamping threads in the convex face thereby produced.

2. The method of making a connector bolt which is characterized by bending into concavoconvex transverse section thin, flat relatively wide strip of suiiicient thickness to form a substantially rigid boltleg and simultaneously stamping, in the convex face thereby produced, threads of less depth than the thickness of the metal whil'e maintaining the inner face smooth and maintaining the rigidity of the bolt leg forming portion of the strip.

3. The method of making a connector bolt with spaced legs which is characterized by rounding leg forming elements and simultaneously stamping threads in their exterior faces while maintaining the width and thickness of said elements substantially unchanged. 7

4. The method of making a connector bolt which is characterized by bending a blank of substantially flat material midway of its length to form a U-shaped member, but without changing the cross sectional area or shape of the legs of the member, and then bending each leg thereby produced about a longitudinal axis to form concavo-convex transverse section and simultaneously impressing threads into the convex face of each of said legs but without substantial change in the cross sectional area.

5. The method of making a connector bolt which is characterized by pressing a substantially flat blank between a smooth convex anvil and a concave die, provided with thread producing ridges, to produce a leg comprising a narrow longitudinal section of an exteriorly threaded cylinder having a smooth interior, without causing the metal to flow longitudinally of the blank.

6. The method of making a connector bolt which is characterized by bending a substantially flat blank of rectangular cross section .with inner and outer faces of equal width to form a leg strip having a concavo-convex cross section with inner and outer faces of equal width, and simultaneously impressing threads in the convex face of said strip and maintaining the inner face of said strip smooth.

7. The method of making a connector bolt which is characterized by bending a substantially flat blank to form a leg strip having a concavoconvex cross section of substantially the same thickness as said blank and, while maintaining its concave inner face smooth, impressing threads in its convex outer face without changing its average thickness.

8. The method of making a connector bolt which is characterized by bending a blank with substantially flat faces into a U-shaped member, and then bending the legs of said member to provide it with a concave-convex cross section and simultaneously impressing threads in the convex face only thereof while maintaining the inner face smooth, both the bending and the thread impressing operations being effected without substantially elongating the legs.

9. A connector bolt of rolled material with its grain structure elongated in the direction of the rolling, said material being pressed to form legs curved transversely of the length of said grain structure into arcuate cross section and provided with impressed external threads, said legs retaining substantially the same thickness as the original metal blank with the original grain elongation in the leg metal being substantially unchanged by the curving of the legs and the formation of the threads therein.

10. A metallic connector bolt comprising a strip, having elongated grain structure as results from rolled production, and pressed to form spaced legs curved transversely of their length and having exterior threads impressed therein while maintaining substantially unchanged the thickness, the width the elongated grain structure and the strength of the strip.

11. A connector bolt comprising spaced legs of concavo-convex cross section with threads impressed therein and of substantially uniform thickness from side to side and with substantially uniform grain structure elongated in the direction of the length of the legs whereby the original grain elongation and strength of roll strip metal from which the bolt is produced is not substantially diminished by the formation of the legs.

12. As a new article of manufacture, a connector bolt made in accordance with the method of claim 1.

13. As a new article of manufacture, a connector bolt made in accordance with the method of claim 2.

14. As a new article of manufacture, a connector bolt made in accordance with the method of claim 4.

15. As a new article of manufacture, a connector bolt made in accordance with the method of claim 8.

PAUL J. McCULLOUGH. JOSEPH PAVELKA. 

